Recently, demands on a small-sized compact camera module are on the increase for use in various multimedia fields including notebook type personal computers, camera phones, PDAs (Personal Digital Assistants), smart phones and toys, and in image input equipment including monitoring cameras and information terminals for video tape recorders.
Generally, the compact camera module is applied to portable communication devices including camera phones, PDAs (Personal Digital Assistants) and smart phones and to various IT (Information Technology) devices.
The camera module is generally manufactured using an image sensor or a photo-electric conversion device of a CCD (Charge Coupled Apparatus) type or a CMOS (Complementary Metal Oxide Semiconductor) type to converge light from an object to a photosensitive element, to form an image of the object and display the image on a display device.
Furthermore, the camera module is manufactured to enable a focus adjustment for adjusting a size of an image, where a driving source is installed and a plurality of lenses is moved to change a relative distance for adjustment of an optical focal length.
At this time, when a user attempts to capture an image, a focus of the camera module is blurred by vibration of the user's hands, and therefore a reduction in the quality of a captured image may occur. That is, when there is vibration in a user's hands which hold the camera module, the subject image moves to a different location and therefore the focus of the camera vibrates, so that the phenomenon of blurring of the subject image may occur.
A hand-shake correction mechanism is a device applied to preventing a reduction in the quality of a captured image caused by hand-shake during photographing. A conventional hand-shake correction mechanism was mainly used for a digital camera. This is because a large-sized camera module is easier in application of the hand-shake correction mechanism than a compact-sized camera module used for mobile phones.
However, concomitant with demands requiring a high quality image in a compact-sized camera module as that of a digital camera, a hand-shake correction mechanism has been applied to mobile compact-sized camera module, and as a result, attempts at developing and researching the hand-shake correction mechanism have been actively made.
The conventional hand-shake correction mechanism can be generally classified into four categories: that is, a hand-shake correction optical lens moving method, an image sensor moving method, a prism refraction method, and camera module tilting method.
FIGS. 1 and 2 are perspective views illustrating a hand-shake correction camera module by the typical tilting method.
Referring to FIGS. 1 and 2, a module part (10), which is an image sensor converting an optical signal to an electrical signal, includes a lens assembly formed with a plurality of lenses for concentrating light, a cover encasing the lens assembly and a PCB (Printed Circuit Board) processing a signal from the image sensor.
The module part (10) is inserted into a case (20) to tilt in response to movement of a moving part, where the module part (10) tilts to ‘a’ direction and ‘b’ direction in response to movement of the module part (10) caused by hand-shake. At this time, referring to FIG. 2, the module part (10) may tilt to only one direction of ‘a’ direction or ‘b’ direction, but largely tilts to both directions because the hand-shake mostly occurs three dimensionally.
However, a rotational movement to ‘c’ direction (rotation of module part, 10) may occur during tilting movement, and in this case, a focus is disadvantageously warped to correct the hand-shake. On top of that, there may occur problems such as damages to the module part (10) and the case (20) caused by contact with the case (20) during rotating movement of the module part (10) and damages to the moving part (10) caused by excessive rotating movement of the module part (10).